18640831 has 4 divisors (see below), whose sum is σ = 20335464. Its totient is φ = 16946200.

The previous prime is 18640813. The next prime is 18640841. The reversal of 18640831 is 13804681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13804681 = 11 ⋅1254971.

It is a cyclic number.

It is not a de Polignac number, because 18640831 - 2¹³ = 18632639 is a prime.

It is a super-2 number, since 2×18640831² = 694961160741122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18640793 and 18640802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18640841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 847300 + ... + 847321.

It is an arithmetic number, because the mean of its divisors is an integer number (5083866).

Almost surely, 2^18640831 is an apocalyptic number.

18640831 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

18640831 is a deficient number, since it is larger than the sum of its proper divisors (1694633).

18640831 is a wasteful number, since it uses less digits than its factorization.

18640831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1694632.

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 18640831 is about 4317.5028662411. The cubic root of 18640831 is about 265.1480411695.

The spelling of 18640831 in words is "eighteen million, six hundred forty thousand, eight hundred thirty-one".